3,456 research outputs found
Image-Image Domain Adaptation with Preserved Self-Similarity and Domain-Dissimilarity for Person Re-identification
© 2018 IEEE. Person re-identification (re-ID) models trained on one domain often fail to generalize well to another. In our attempt, we present a 'learning via translation' framework. In the baseline, we translate the labeled images from source to target domain in an unsupervised manner. We then train re-ID models with the translated images by supervised methods. Yet, being an essential part of this framework, unsupervised image-image translation suffers from the information loss of source-domain labels during translation. Our motivation is two-fold. First, for each image, the discriminative cues contained in its ID label should be maintained after translation. Second, given the fact that two domains have entirely different persons, a translated image should be dissimilar to any of the target IDs. To this end, we propose to preserve two types of unsupervised similarities, 1) self-similarity of an image before and after translation, and 2) domain-dissimilarity of a translated source image and a target image. Both constraints are implemented in the similarity preserving generative adversarial network (SPGAN) which consists of an Siamese network and a CycleGAN. Through domain adaptation experiment, we show that images generated by SPGAN are more suitable for domain adaptation and yield consistent and competitive re-ID accuracy on two large-scale datasets
Unsupervised Domain Adaptation in the Dissimilarity Space for Person Re-identification
Person re-identification (ReID) remains a challenging task in many real-word
video analytics and surveillance applications, even though state-of-the-art
accuracy has improved considerably with the advent of deep learning (DL) models
trained on large image datasets. Given the shift in distributions that
typically occurs between video data captured from the source and target
domains, and absence of labeled data from the target domain, it is difficult to
adapt a DL model for accurate recognition of target data. We argue that for
pair-wise matchers that rely on metric learning, e.g., Siamese networks for
person ReID, the unsupervised domain adaptation (UDA) objective should consist
in aligning pair-wise dissimilarity between domains, rather than aligning
feature representations. Moreover, dissimilarity representations are more
suitable for designing open-set ReID systems, where identities differ in the
source and target domains. In this paper, we propose a novel
Dissimilarity-based Maximum Mean Discrepancy (D-MMD) loss for aligning
pair-wise distances that can be optimized via gradient descent. From a person
ReID perspective, the evaluation of D-MMD loss is straightforward since the
tracklet information allows to label a distance vector as being either
within-class or between-class. This allows approximating the underlying
distribution of target pair-wise distances for D-MMD loss optimization, and
accordingly align source and target distance distributions. Empirical results
with three challenging benchmark datasets show that the proposed D-MMD loss
decreases as source and domain distributions become more similar. Extensive
experimental evaluation also indicates that UDA methods that rely on the D-MMD
loss can significantly outperform baseline and state-of-the-art UDA methods for
person ReID without the common requirement for data augmentation and/or complex
networks.Comment: 14 pages (16 pages with references), 7 figures, conference ECC
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